For various reasons, certain general managers on contending teams have a stronger tendency than others to make big moves for their clubs right before the July 31st non-waiver trading deadline.

These reasons can include, but are no limited to:

-A specific need for an upgrade at a certain position-A desire to block a rival from acquiring the same player-A desire to win now because the team's star will leave town in the off-season-A foresight of good value-A sense of the dramatic

The smarter GMs who have decided that their teams are sellers usually tend to trade off their commodities long before July 31st; at a time when they perceive that their player's value is at its highest.

The buyers will attempt to wait them out, seeking to force the sellers hand at the very last minute when they become desperate.

This is what happens on our ideal trading deadline day, and we've seen it happen in the recent past with iconic trades like the Red Sox dealings of Nomar Garciaparra and Manny Ramirez.

But because the Red Sox have a dynamic team and a potentially dominant core in place for the future, I very much doubt that Theo Epstein will be overly aggressive at this year's trading deadline.

Kenny Williams, Chicago White Sox

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Eager to get his club back to the World Series, where they haven't been since capturing a world championship in 2005, Kenny Williams has been among the most active general managers at the non-waiver trading deadline in the past few years.

In 2008, Williams sent Nick Massett and Danny Richar to the Reds in exchange for Ken Griffey Jr.

The future Hall of Famer managed just three homers and a .260 average in 41 games with the Sox, and was ultimately a bust.

In 2009 Williams acquired former NL Cy Young winner Jake Peavy from the Padres in exchange for a trio of minor league pitchers. Because of injuries, Peavy too has been a disappointment thus far in Chicago; but he still has time to rescue that notion.

Last season, Williams sent youngsters Daniel Hudson and David Holmberg to the Diamondbacks for the ever-traded Edwin Jackson. The soon-to-be free agent can be hit-or-miss in his starts, but he has been a welcome addition to the White Sox rotation to this point.

He's a more than serviceable third or fourth starter.

Standing 43-43 as of yesterday, Chicago finds themselves 3.5 games behind division-leading Cleveland and two games behind rival Detroit.

Williams could stand to find a major upgrade in left field (for Juan Pierre) or at third base (for Brett Morel and Mark Teahen) to solidify the middle of the White Sox lineup.

With the future of his job now seemingly insecure, I'd expect Williams to make yet another big move before 4 PM on July 31st.

Mike Rizzo, Washington Nationals

The Washington Nationals, and their general manager Mike Rizzo, supposedly have a large budget for player acquisitions with which to play around.

The baseball world got a small taste of this last summer when the Nats signed outfielder Jayson Werth to a surprise seven-year, $126 million contract.

Whether or not Werth will be able to live up to the deal is irrelevant (he won't, more than likely). The factor to focus on here is that, for the first time in their history, this organization has a lot of money to spend on premium talent.

They've come quite a long way since watching players like Larry Walker and Vlad Guerrero leave what was then the Montreal Expos because of financial hold-ups.

Owning the rights to perhaps the top young professional hitter and pitcher in baseball in Bryce Harper and Stephen Strasburg, the Washington Nationals are most certainly a team of the future.

With a 43-43 record in the rigorous NL East despite playing just 28 games with their best player, third baseman Ryan Zimmerman, Washington may also be a team of right now.

The 2011 Nationals have received surprise contributions both from the back end of their rotation and infielders Ian Desmond, Danny Espinosa and Michael Morse. They could certainly stand to add another bat in the outfield.

Rumors are swirling that Mike Rizzo is in hot pursuit of that very commodity. Even though they're currently 6.5 games out of the NL Wild Card spot, A big trade could help put Washington right in the thick of things come September.

Doug Melvin, Milwaukee Brewers

The Brewers have been on the quieter side of things during the trading deadline in recent years. But General Manager Doug Melvin certainly knows when the time is right to pull the trigger.

Back in 2008, Milwaukee made major waves by acquiring C.C. Sabathia from the Indians in early-July for a five-player package centered around Matt LaPorta.

Sabathia went 11-2 down the stretch for Milwaukee with a 128:25 strikeout to walk ratio over 130 innings as the Brew Crew avoided collapse and earned a wild card birth; giving the team its first playoff appearance since 1982.

None of the players in the LaPorta deal managed to pan out, making the trade a win for the Brewers even though Sabathia left for the gold-lined pockets of the Yankees over the winter.

With star first baseman (and maybe current NL MVP leader) Prince Fielder set to test free agency at the conclusion of this season, the Brewers are entirely in win-now mode.

They've fought valiantly in the competitive NL Central, bunched up at 45-41 with the Cardinals (46-40), Pirates (45-41) and Reds (43-43).

Although they'll likely retain Ryan Braun and their elite trio of starting pitchers in Yovani Gallardo, Zack Greinke and Shawn Marcum, the Brew Crew have a lot to lose if they don't make a run this season.

Look for Melvin to really shore up their bullpen with whatever big targets are on the board; particularly Heath Bell or Francisco Rodriguez.

Jon Daniels, Texas Rangers

Jon Daniels has certainly made his far share of trades since arriving in Arlington.

Though his initial deal that sent Alfonso Soriano to the Nationals was met with a lot of criticism, his more recent moves have been much more well received.

A trio of July deals have come to define the Jon Daniels era to this point. The first was a 2006 trade which sent Kevin Mench, Layne Nix and Francisco Cordero to the Milwaukee Brewers for Carlos Lee and Nelson Cruz.

Although Carlos was a bit of a disappointment and left for Houston and $100 million in the offseason, Cruz has become an All-Star and major contributor with the Rangers the past few years.

The second was a 2007 deal which sent slugger Mark Teixeira to the Braves in exchange for Jarrod Saltalamacchia and four prospects; three of whom turned out to be Elvis Andrus, Neftali Feliz and Matt Harrison.

The third was last season's acquisition of Cliff Lee from the Mariners in exchange for a package centered around Justin Smoak.

Lee helped carry the franchise to its first ever appearance in the World Series (beating the Rays once and the Yankees twice), but ultimately lost both his starts against Tim Lincecum during the final interleague showdown.

Daniels has proven to be very aggressive come the trade deadline.

Although Texas has a powerful offense, they have been linked with Mets outfielder Carlos Beltran who had one of the greatest postseasons in baseball history after being traded to the Astors in 2004.

Texas could also use bullpen help, but Daniels might decide to go after both.